Army Corps releases final draft of options for aquatic nuisance controls

Last week, the U.S. ArmyCorps of Engineersreleased the final draft of its inventory of available controls for aquatic nuisance species of concern, which includes Asian carp.

The final draft comes after a public comment period, which was open through Feb. 17. During the public comment period, the corps asked for additional suggestions for controls of the flow of aquatic nuisance species between the Great Lakes and Mississippi watershed.

The corps added three ways to keep nuisance species from passing between the two water bodies, and released its final report as part of the Great Lakes Interbasin Study, which will examine methods for stopping the transfer of aquatic species between the two bodies of water. These three new controls would aim to stop the passage of not just Asian carp, but organisms such as zebra mussels, non-native algae and crustaceans -- 39 total -- the corps has identified as aquatic nuisance species.

"There were three items we changed," said Gary O'Keefe, the study's project manager. "First, we added a lethal temperature. We had considered hot temperatures, but had not considered freezing. We're also considering carbon dioxide pellet blasting and dessication."

Other methods already included in the report are controls such as acoustic fish deterrents, overfishing for Asian carp, and biological controls.

During the public comment period, the corps received 195 comments from people ranging from private citizens and nonprofits to state departments of natural resources.

The added controls suggest lowering the canal artificially in order for it to freeze, as well as flash-freezing organisms with carbon dioxide pellets, or lowering the water levels of some areas in the potential contact points between the Mississippi River basin and the Great Lakes to the point where organisms dry out and die, said Mark Cornish, biologist with the U.S. Army Corps of Engineers.

"Anything that has the ability to float with water and get away usually will, but with dessication, plants rooted to the bottom and zebra mussels will be affected," said Cornish.

Dessication could be used as a management tool to reduce the number of invasives that come through the system, he said.

The interbasin study has an estimated completion date of 2015, which some organizations think is too late.

"And that's just the study completion estimate, not the shovel-in-the-dirt start date," said Cheryl Kallio, associate director of the environmental nonprofit Freshwater Future.

Freshwater Future remains steady in its stance of restoring the hydrological divide between the Great Lakes and the Mississippi River system, and Asian carp ranks high on its list of concern.

Species of Asian carp, including silver and bighead carp, have already pressed up to the electric barrier in place to keep carp out of the Great Lakes, and a bighead carp was caught in Lake Calumet, past the electric barriers and five miles downstream of Lake Michigan.

The Chicago Shipping Canal's construction in the early 1900s connected the two bodies of water, and since, has served as a swinging door not only for shipping and pleasure boating, but for aquatic invasive species.

Kallio cites the "Restoring the Natural Divide" report, which the Great Lakes and St. Lawrence Cities Initiative and the Great Lakes Commission put together regarding permanent hydrological separation. The report, identifying 20 possible barrier locations in the Chicago area, found that hydrological separation was feasible by 2029.

"That report shows that separating the Great Lakes and the Mississippi River basins to prevent the spread of Asian carp and other invasive species is not only feasibly both technically and economically, but is also a natural step toward much-needed action to improve Chicago's water infrastructure," said Jennifer McKay, policy specialist with Tip of the Mitt Watershed Council in Petoskey. "This is further justification that we should get construction started sooner than wait another three to five years for the (Army corps) to study the problem."

The Great Lakes Commission report is being considered by the Army corps, said Kallio.

A significant roadblock remains the Chicago Area Waterway System, which would require an overhaul before a permanent separation is put in place. Currently, Chicago's sewer and streetwater system releases wastewater into the shipping canal during a flooding event. Too, the shipping industry is concerned over the canal's potential closure.

"The amount of impacts you need to address in the Chicago area is important," said O'Keefe. "There would be a lot of impacts on water management throughout the area, impacts on water quality and impacts on navigation. We have to determine how each alternative impacts those uses, and also how we have to go about mitigating those impacts."

Kallio hopes to keep up the momentum of concern about invasives in the Great Lakes.

"We just need to make sure we stay in communication with our communities about this," said Kallio. "We just have to make sure that people don't forget. We need to keep these conversations going and need to make sure it all filters back up to members of Congress."